“Metadata” associated with video and television programming guides such as an Electronic Programming Guide (EPG) or an Interactive Program Guide (IPG) is transmitted via DTV (digital television) transmissions, IPTV (Internet Protocol Television), and/or a digital delivery network such as the Internet. The metadata may include information pertaining to video content (e.g., title), television tuning information (e.g., frequency, channels or sub channels), rating (e.g., parental control purposes such as locked out channels), closed caption data, and/or other data (e.g., control data for Video on Demand or Pay Per View).
Further relating to the field of video content control for the well known NTSC, PAL, and SECAM standard color television systems, color picture information is transmitted on a subcarrier signal. In this case of the NTSC system the subcarrier signal has a frequency of about 3.58 MHz and in the case of the PAL system a frequency of about 4.43 MHz. In both systems the precise color at any point in the picture is determined by the phase of this subcarrier signal relative to some reference phase, while the degree of saturation of the color is determined by the amplitude of the subcarrier signal.
In order for a television receiver to correctly reproduce colors, the receiver requires information concerning the above-mentioned reference phase. This information is transmitted as part of the video signal in the form of a burst of about nine cycles of the subcarrier signal following the horizontal synchronizing pulse, and is referred to as the color burst. This color burst in the television receiver phase-locks a crystal oscillator circuit, thus generating a continuous subcarrier signal at the reference phase which is then used to demodulate the color information. It is normal for the phase-locked crystal oscillator circuit in the television receiver to have a fairly long time constant, on the order of a few milliseconds. The long time constant insures that the crystal oscillator circuit will ignore short term phase perturbations of the color burst signal as might be caused by noise. This color burst has been used for NTSC etc. standard television to provide copy protection, as described below.